Get out of the house. The old standard "date night" can be a great relationship booster. If you can get a sitter once in awhile, go out for dinner or a movie together. Emotional intimacy sparks sexual intimacy.
Your friends were always there for you, being supportive in bad times and taking you out to celebrate victories, but now those same friends seem a little confused about how to behave now that you're a mom.
The friends who have children of their own don't present a problem. You now have another thing in common with them and you can get together for play dates and conversation.